The present invention relates to the production of brazeable pipes particularly for use as headers in condensers, evaporators, and radiators in automobile air conditioning systems.
A heat exchanger includes cylindrical headers which introduce a cooling medium into the tubes and discharge it after it has circulated throughout the tubes. The cylindrical headers, hereinafter referred to as header pipes, are made by rolling a brazing sheet into a cylinder. The brazing sheet is made of a core sheet coated with a brazing substance on one or both surfaces. The headers, the tubes and other components such as fins are brazed to one another at vacuum or with the use of flux.
So far the header pipes have been produced in the following manner:
The brazing sheet is prepared and rolled until its both ends are butted. The butted ends are electrically welded to form a seamed pipe. Then a given number of holes are made in the header pipe for allowing the connection of tubes therein.
To make the holes a punching pressure is applied to the header pipes, but under the pressure the pipes are in danger of crushing or deforming because of the relatively weak welded seams. To avoid such problems, the holes are made by a milling. The milling unavoidably produces flashes, so that the trimming of flashes is required. This is a time- and a labor-consuming work. In order to keep the header pipes tough the holes must be off the welded seam. It is required to ascertain whether or not the spot to be holed is off the welded seam.
Accordingly an object of the present invention is to provide a process for producing breazeable pipes particularly for use as header pipes without the possibility of crush and deformation.
Another object of the present invention is to provide a process for producing breazeable pipes which enables easy removal of flashes possibly caused in milling the holes.
A further object of the present invention is to provide a process for producing breazeable pipes having holes produced off the seam.
Other objects and advantages of the present invention will become more apparent from the following detailed description, when taken in conjunction with the accompanying drawings which show, for the purpose of illustration only, one embodiment in accordance with the present invention.